U.S. patent application number 10/979365 was filed with the patent office on 2005-08-11 for enhancing properties by the use of nanoparticles.
Invention is credited to Disalvo, Anthony L., Mordas, Carolyn J..
Application Number | 20050175649 10/979365 |
Document ID | / |
Family ID | 34549441 |
Filed Date | 2005-08-11 |
United States Patent
Application |
20050175649 |
Kind Code |
A1 |
Disalvo, Anthony L. ; et
al. |
August 11, 2005 |
Enhancing properties by the use of nanoparticles
Abstract
Composite materials comprising nanoparticles functionalized with
metals are disclosed. The composite materials may be used in a
variety of applications, including in coating compositions,
cosmetic and pharmaceutical compositions, absorbent articles, and
the like.
Inventors: |
Disalvo, Anthony L.;
(Bernardsville, NJ) ; Mordas, Carolyn J.;
(Princeton, NJ) |
Correspondence
Address: |
PHILIP S. JOHNSON
JOHNSON & JOHNSON
ONE JOHNSON & JOHNSON PLAZA
NEW BRUNSWICK
NJ
08933-7003
US
|
Family ID: |
34549441 |
Appl. No.: |
10/979365 |
Filed: |
November 1, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60515758 |
Oct 30, 2003 |
|
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|
Current U.S.
Class: |
424/401 ;
428/403 |
Current CPC
Class: |
A61K 8/0245 20130101;
A61K 8/25 20130101; A61L 2300/624 20130101; A61K 9/5115 20130101;
A61L 2300/104 20130101; A61L 15/42 20130101; A61Q 19/00 20130101;
A61L 15/46 20130101; A61L 15/18 20130101; C09D 1/00 20130101; A61K
8/19 20130101; Y10T 428/2991 20150115; A61L 2300/102 20130101; A61F
13/8405 20130101; A01N 25/28 20130101; A61K 2800/621 20130101; A61Q
11/00 20130101; B82Y 5/00 20130101; A61K 2800/413 20130101; A61K
8/0241 20130101; A61F 2013/8426 20130101 |
Class at
Publication: |
424/401 ;
428/403 |
International
Class: |
B32B 015/02; B32B
018/00; A61K 007/00 |
Claims
We claim:
1. A composite material comprising (a) an exfoliated nanoparticle
having a surface and (b) a metal selected from Groups 3 to 12,
aluminum and magnesium, wherein the metal is loaded onto the
surface of the nanoparticle.
2. The composite material of claim 1, wherein the metal is loaded
onto the surface of the nanoparticle by intercalation.
3. The composite material of claim 1, wherein the metal is loaded
onto the surface of the nanoparticle by adsorption.
4. The composite material of claim 1, wherein the metal is loaded
onto the surface of the nanoparticle by ion exchange.
5. The composite material of claim 1, wherein the metal is selected
from the group consisting of silver, copper, zinc, manganese,
platinum, palladium, gold, calcium, barium, aluminum, iron, and
mixtures thereof.
6. The composite material of claim 1, wherein the nanoparticle
comprises a nanoclay.
7. The composite material of claim 1, wherein the nanoparticle
comprises exfoliated Laponite.
8. A solution comprising the composite material of claim 1.
9. A solid comprising the composite material of claim 1.
10. A gel comprising the composite material of claim 1.
11. A composition comprising the composite material of claim 1.
12. The composition of claim 11, further comprising one or more
adjunct ingredients and a carrier medium.
13. The composition of claim 12, wherein the adjunct ingredients
are selected from surfactants and charged functionalized
molecules.
14. The composition of claim 12, wherein the carrier medium
comprises is an aqueous carrier medium.
15. A cosmetic or pharmaceutical composition comprising the
composite material of claim 1.
16. The composition of claim 15, further comprising an active agent
selected from skin lightening agents, skin pigmentation darkening
agents, anti-acne agents, sebum modulators, shine control agents,
anti-microbial agents, anti-fungals, anti-inflammatory agents,
anti-mycotic agents, anti-parasite agents, external analgesics,
sunscreens, photoprotectors, antioxidants, keratolytic agents,
detergents, surfactants, moisturizers, nutrients, vitamins, energy
enhancers, anti-perspiration agents, astringents, deodorants, hair
removers, firming agents, anti-callous agents, and agents for hair,
nail, or skin conditioning.
17. A method of making a composite material comprising an
exfoliated nanoparticle having a metal coating, which method
comprises: (a) reducing a metal ion to metal; (b) exfoliating a
starting material to form an exfoliated nanoparticle; and (c)
contacting the metal with the exfoliated nanoparticle, whereby
steps (a) and (b) may be performed sequentially in any order or
simultaneously and the metal is loaded onto the surface of the
exfoliated nanoparticle.
18. The method of claim 17, wherein the metal is loaded onto the
surface of the nanoparticle by intercalation.
19. The method of claim 17, wherein the metal is loaded onto the
surface of the nanoparticle by adsorption.
20. The method of claim 17, wherein the metal is loaded onto the
surface of the nanoparticle by ion exchange.
21. The method of claim 17, wherein the metal is selected from the
group consisting of silver, copper, zinc, manganese, platinum,
palladium, gold, calcium, barium, aluminum, iron, and mixtures
thereof.
22. The method of claim 17, wherein the nanoparticle comprises a
nanoclay.
23. The method of claim 22, wherein the nanoparticle comprises
exfoliated Laponite.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority from U.S. provisional
application Ser. No. 60/515,758 filed Oct. 30, 2003.
FIELD OF THE INVENTION
[0002] The present invention relates to composite materials that
are functionalized nanoparticles and in particular, metal-loaded
nanoclays. Additionally, the present invention relates to a method
of forming such composite materials.
BACKGROUND OF THE INVENTION
[0003] For centuries, silver metal has been known to be an agent
capable of killing many different microbial species. It was
commonly used to purify drinking solutions or administered to sick
individuals before the existence of modern antibiotics. Even after
the discovery of penicillin and its descendents, colloidal silver
solutions were often used in cases in which troublesome bacteria
had become resistant to antibiotics.
[0004] Colloidal silver solutions are commercially available today.
They are often unstable, however, and have a short shelf life. This
is due to the tendency of the silver particles to aggregate and
form clusters so large that they are no longer suspended in
solution. For this reason, undesirable gelling agents are added to
solutions to keep the silver particles suspended by preventing
particle aggregation. Another problem of the commercially available
solutions is that the majority of the silver content is usually
found to be silver ions. This poses a large problem in medical
applications where silver ions rapidly combine with ubiquitous
chloride to form an insoluble white precipitate.
[0005] Nanoparticles have been known to be used as fillers as
disclosed in U.S. Pat. No. 6,492,453, as coatings as disclosed in
U.S. 2003/0185964 and as foam components as disclosed in U.S. Pat.
No. 6,518,324.
[0006] Nanoparticle systems are disclosed in U.S. 2002/0150678 as
being used in a composition and a method to impart surface
modifying benefits to soft and hard surfaces. In particular, this
application discloses a soft surface coating for articles such as
fabrics and garments.
[0007] Inorganic particulates, such as, clays, silicates, and
alumina have been widely used in combination with adjunct detergent
and laundry compounds to impart some form of antistatic control
and/or fabric softening benefit.
[0008] The present invention relates to composite materials
comprising metal loaded onto exfoliated nanoparticles. Such
functionalized nanoparticles may be incorporated into solid and
liquid materials to enhance or modify their bulk physical and
performance characteristics. In one embodiment, the metal is silver
and the nanoparticle comprises a nanoclay. Silver ion is reduced to
its neutral metal state (Ag.sup.0) and loaded onto the nanoclay.
Silver-coated nanoclays in particular have excellent antimicrobial
properties, and represent a less expensive alternative to the use
of colloidal silver solutions. Such nanoparticles made according to
the invention are stable and use less silver metal to generate the
same surface area as solid silver particles, making them more cost
efficient.
SUMMARY OF THE INVENTION
[0009] The invention provides a composite material comprising (a)
an exfoliated nanoparticle having a surface and (b) a metal
selected from Groups 3 to 12, aluminum and magnesium, wherein the
metal is loaded onto the surface of the nanoparticle.
[0010] The invention also provides a method of making a composite
material comprising an exfoliated nanoparticle having a metal
coating, which method comprises: (a) reducing a metal ion to metal;
(b) exfoliating a starting material to form a nanoparticle; and (c)
contacting the metal with the exfoliated nanoparticle, whereby
steps (a) and (b) may be performed sequentially in any order or
simultaneously and the metal is loaded onto the surface of the
exfoliated nanoparticle.
[0011] The invention further provides solutions, solids, gels,
coating compositions, cosmetic and pharmaceutical compositions, and
articles of manufacture comprising such a composite material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 shows the particle size distribution of the material
of Example 1.
[0013] FIG. 2 shows the particle size distribution of the material
of Example 5.
[0014] FIG. 3 shows the particle size distribution of the material
of Example 6.
[0015] FIG. 4 shows the particle size distribution of the material
of Example 7.
DETAILED DESCRIPTION OF THE INVENTION
[0016] Every limit given throughout this specification includes
every lower or higher limit, as the case may be, as if such lower
or higher limit was expressly written herein. Every range given
throughout this specification includes every narrower range that
falls within such broader range, as if such narrower ranges were
all expressly written herein.
[0017] Nanoparticles as used herein means particles (including but
not limited to rod-shaped particles, disc-shaped particles,
platelet-shaped particles, tetrahedral-shaped particles), fibers,
nanotubes, or any other materials having dimensions on the nano
scale. In one embodiment, the nanoparticles have an average
particle size of about 1 to about 1000 nanometers, preferably 2 to
about 750 nanometers. That is, the nanoparticles have a largest
dimension (e.g., a diameter or length) of about 1 to 1000 nm.
Nanotubes can include structures up to 1 centimeter long,
alternatively with a particle size from about 2 to about 50
nanometers. Nanoparticles have very high surface-to-volume ratios.
The nanoparticles may be crystalline or amorphous. A single type of
nanoparticle may be used, or mixtures of different types of
nanoparticles may be used. If a mixture of nanoparticles is used
they may be homogeneously or non-homogeneously distributed in the
composite material or a system or composition containing the
composite material.
[0018] Non-limiting examples of suitable particle size
distributions of nanoparticles are those within the range of about
2 nm to less than about 750 nm, alternatively from about 2 nm to
less than about 200 nm, and alternatively from about 2 nm to less
than about 150 nm. It should also be understood that certain
particle size distributions may be useful to provide certain
benefits, and other ranges of particle size distributions may be
useful to provide other benefits (for instance, color enhancement
requires a different particle size range than the other
properties). The average particle size of a batch of nanoparticles
may differ from the particle size distribution of those
nanoparticles. For example, a layered synthetic silicate can have
an average particle size of about 25 nanometers while its particle
size distribution can generally vary between about 10 nm to about
40 nm. It should be understood that the particle size distributions
described herein are for nanoparticles when they are dispersed in
an aqueous medium and the average particle size is based on the
mean of the particle size distribution.
[0019] According to the invention, the nanoparticles are
exfoliated. In particular, a starting material is exfoliated or
disbursed to form the nanoparticles. Such starting material may
have an average size of up to about 50 microns (50,000
nanometers).
[0020] The nanoparticle may comprise for example natural or
synthetic nanoclays, including those made from amorphous or
structured clays.
[0021] In one embodiment, the exfoliated nanoparticle is a
nanoclay. In a further embodiment, the nanoparticle is a swellable
nanoclay or adduct thereof. A swellable nanoclay has weakly bound
ions in interlayer positions that may be hydrated or may absorb
organic solvents. These swellable nanoclays generally possess a low
cationic or anionic charge, i.e. less than about 0.9 units of
charge per unit cell.
[0022] As used herein, "adducts" means oil swellable nanoclays,
i.e. those that swell in organic, non-aqueous solvents such as
polar and nonpolar solvents. They may be prepared by reacting a
water swellable nanoclay with an organic material that binds to the
swellable nanoclay. Examples of such binding organic materials
include, but are not limited to, a quaternary ammonium compound
having the structure:
R.sub.1R.sub.2R.sub.3R.sub.4N+ X-
[0023] wherein
[0024] R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are each independently
selected from H, a C.sub.1 to C.sub.22 alkyl, a C.sub.1 to C.sub.22
alkenyl, and a C.sub.1 to C.sub.22 aralkyl, provided that at least
one of the R groups is such an alkyl, alkenyl or aralkyl; and
[0025] X is the water swellable nanoclay.
[0026] The swellable nanoclay may be amorphous or structured, i.e.,
including sheets or layers, wherein a combination of such layers is
referred to as a lattice structure. Examples of suitable nanoclays
having lattice structures include the pyrophillite (dioctahedral)
type, the talc (trioctahedral) type, or mixtures thereof. Classes
of suitable structured swellable nanoclays include, but are not
limited to the smectite nanoclays, sepiolite nanoclays, zeolite
nanoclays, palygorskite nanoclays, or mixtures thereof.
[0027] Examples of amorphous swellable nanoclays include allophone
and imogolite.
[0028] In one embodiment, the nanoparticles are made from a
starting material such as Nanomer 1.34TCN (available from Nanocor)
having a particle size of 10 to 18 microns (10000-18000
nanometers). In another embodiment, the nanoparticles are made from
PGV (also available from Nanocor) having a particle size of 20 to
25 microns. In another embodiment, exfoliated PGV having a particle
size range of 1-3 nanometers is used. In other embodiments, Nanomer
1.34TCN and Nanomer 1.30E having a particle size range of 1-9
nanometers is used.
[0029] Boehmite alumina can have an average particle size
distribution from 2 to 750 nm.
[0030] Layered clay minerals can be used as starting materials for
the exfoliated nanoparticles. The layered clay minerals suitable
for use in the present invention include those in the geological
classes of the smectites, the kaolins, the illites, the chlorites,
the attapulgites and the mixed layer clays. Typical examples of
specific clays belonging to these classes are the smectices,
kaolins, illites, chlorites, attapulgites and mixed layer clays.
Smectites, for example, include montmorillonite, bentonite,
pyrophyllite, hectorite, saponite, sauconite, nontronite, talc,
beidellite, volchonskoite, stevensite, and vermiculite. In one
embodiment, montmorillonite nanoclay is preferred. See U.S. Pat.
No. 5,869,033, which is incorporated by reference herein. Kaolins
include kaolinite, dickite, nacrite, antigorite, anauxite,
halloysite, indellite and chrysotile. Illites include bravaisite,
muscovite, paragonite, phlogopite and biotite. Chlorites include
corrensite, penninite, donbassite, sudoite, pennine and
clinochlore. Attapulgites include sepiolite and polygorskyte. Mixed
layer clays include allevardite and vermiculitebiotite. Variants
and isomorphic substitutions of these layered clay minerals offer
unique applications.
[0031] Layered clay minerals may be either naturally occurring or
synthetic. For example, natural or synthetic hectorites,
montmorillonites and bentonites may be used as the starting
material for the nanoparticles.
[0032] Natural clay minerals typically exist as layered silicate
minerals and less frequently as amorphous minerals. A layered
silicate mineral has SiO.sub.4 tetrahedral sheets arranged into a
two-dimensional network structure. A 2:1 type layered silicate
mineral has a laminated structure of several to several tens of
silicate sheets having a three layered structure in which a
magnesium octahedral sheet or an aluminum octahedral sheet is
sandwiched between two sheets of silica tetrahedral sheets.
[0033] A sheet of an expandable layer silicate has a negative
electric charge, and the electric charge is neutralized by the
existence of alkali metal cations and/or alkaline earth metal
cations. Smectite or expandable mica can be dispersed in water to
form a sol with thixotropic properties. Further, a complex variant
of the smectite type clay can be formed by the reaction with
various cationic organic or inorganic compounds. An example of such
an organic complex, an organophilic clay in which a
dimethyldioctadecyl ammonium ion (a quaternary ammonium ion) is
introduced by cation exchange. This has been industrially produced
and used as a gellant of a coating.
[0034] Synthetic nanoclays may be employed in the invention. With
appropriate process control, the processes for the production of
synthetic nanoclays does indeed yield primary particles that are
nanoscale. However, the particles are not usually present in the
form of discrete particles, but instead predominantly assume the
form of agglomerates due to consolidation of the primary particles.
Such agglomerates may reach diameters of several thousand
nanometers, such that the desired characteristics associated with
the nanoscale nature of the particles cannot be achieved. The
particles may be deagglomerated, for example, by grinding as
described in EP-A 637,616 or by dispersion in a suitable carrier
medium, such as water or water/alcohol and mixtures thereof.
[0035] Synthetic materials for making suitable nanoclays include
layered hydrous silicate, layered hydrous aluminum silicate,
fluorosilicate, mica-montmorillonite, hydrotalcite, lithium
magnesium silicate and lithium magnesium fluorosilicate. An example
of a substituted variant of lithium magnesium silicate is where the
hydroxyl group is partially substituted with fluorine. Lithium and
magnesium may also be partially substituted by aluminum. Lithium
magnesium silicate may be isomorphically substituted by any member
selected from the group consisting of magnesium, aluminum, lithium,
iron, chromium, zinc and mixtures thereof.
[0036] Synthetic hectorite, for example as commercially marketed
under the trade name LAPONITE.TM. by Southern Clay Products, Inc.,
may be used as a starting material for the nanoparticles. There are
many grades or variants and isomorphous substitutions of
LAPONITE.TM. marketed. Examples of commercial hectorites are
LAPONITE B.TM., LAPONITE S.TM., LAPONITE XLS.TM., LAPONITE RD.TM.,
LAPONITE XLG.TM., and LAPONITE RDS.TM..
[0037] Synthetic hectorites do not contain any fluorine. An
isomorphous substitution of the hydroxyl group with fluorine will
produce synthetic clays referred to as sodium magnesium lithium
fluorosilicates, which may also be used as the starting material.
These sodium magnesium lithium fluorosilicates, marketed as
LAPONITE.TM. and LAPONITE S.TM., may contain fluoride ions of up to
approximately 10% by weight. The fluoride ion content useful in the
compositions described herein is up to about 10 or more percent.
LAPONITE B.TM., a sodium magnesium lithium fluorosilicate, has a
flat, circular, plate-like shape, with an average particle size,
depending on fluoride ion content, of about 25-100 nanometers. For
example, in one non-limiting embodiment, LAPONITE B.TM. having a
diameter of about 25-40 nmand and thinkness of about 1 nm may be
used. Another variant, called LAPONITE S.TM., contains about 6% of
tetrasodium pyrophosphate as an additive.
[0038] In one embodiment, Laponite XLS.TM. is used as the starting
material for the nanoparticle, and silver is loaded thereon as the
metal. Laponite XLS has tetrahedral silicate layers joined by
octahedral magnesium and lithium hydroxyl bridges. This structure
allows for exfoliation and modification by either intercalation or
adsorption of metal to the nanoclay surface. In the case of
intercalation, the metal is inserted between the layers of
nanoclay. In the case of surface adsorption, the metal binds to the
surface of the nanoclay. Laponite XLS is advantageous because it is
synthetically consistent and pure, and exfoliates to form
nanoparticles with minimal effort. The surface of the nanoparticle
is covered with sodium ions to balance out the negative charge of
the many silicate groups.
[0039] The aspect ratio of the exfoliated nanoparticles, in some
cases, is of interest in forming films comprising the composite
material with desired characteristics. The aspect ratio of
dispersions can be adequately characterized by TEM (transmission
electron microscopy).
[0040] The aspect ratio of nanoparticles in one embodiment can be
in the range of 100 to 250. In another embodiment, the aspect ratio
of the nanoparticles is 200 to 350.
[0041] For example, the average aspect ratio of individual
particles of LAPONITE B.TM. is approximately 20-40 and the average
aspect ratio of individual particles of LAPONITE RD.TM. is
approximately 10-15. LAPONITE B.TM. occurs in dispersions as
essentially single clay particles or stacks of two clay particles.
LAPONITE RD.TM. occurs essentially as stacks of two or more single
clay particles.
[0042] In some embodiments, a high aspect ratio may be desirable
for film formation. The aspect ratio of exfoliated nanoparticles
dispersed in a suitable carrier medium, such as water, is also of
interest. The aspect ratio of the nanoparticles in a dispersed
medium is lower where several of the particles are aggregated.
[0043] In certain embodiments, it may be desirable for at least
some individual (non-aggregated) platelet and disc-shaped
nanoparticles to have at least one dimension that is greater than
or equal to about 0.5 nm, and an aspect ratio of greater than or
equal to about 15. Larger aspect ratios may be more desirable for
platelet and disc-shaped nanoparticles than for rod-shaped
nanoparticles.
[0044] The aspect ratio of rod-shaped nanoparticles can be lower
than that of disc-shaped or platelet-shaped nanoparticles while
maintaining adequate film-forming properties. In certain
non-limiting embodiments, it may be desirable for at least some of
the individual rod-shaped nanoparticles to have at least one
dimension that is greater than or equal to about 0.5 nm, and an
aspect ratio of greater than or equal to about 3.
[0045] The aspect ratio of spheroid-shaped nanoparticles is
generally less than or equal to about 5. Nanoparticles preferred
for the embodiments presented here have aspect ratios of less than
or equal to about 250. In other non-limiting embodiments, it may be
desirable for the nanoparticles to have an aspect ratio of less
than about 10.
[0046] According to the invention, one or more metals are used to
functionalize the nanoparticle. In particular, they are loaded onto
the exfoliated nanoparticle by one of a variety of methods
including intercalation, adsorption, or ion exchange.
Advantageously, the metal retains its valuble properties, for
example in the case of silver its anti-microbial properties, while
on the nanoparticle. The term loaded, as used herein, includes
complete coverage of the surface of the nanoparticle, or
alternatively, only a portion thereof.
[0047] In one embodiment, the metal is selected from Groups 3 to 12
of the Periodic Table of Elements, aluminum, and magnesium.
Preferably, the metal is selected from silver, copper, zinc,
manganese, platinum, palladium, gold, calcium, barium, aluminum,
iron, and mixtures thereof. In a particularly preferred embodiment,
the metal is silver.
[0048] The metal or metals may be selected based on the desired
effect to be achieved through use of the composite material. For
example, silver may be selected for its known anti-microbial
properties.
[0049] The metal may be loaded onto the nanoparticle via
intercalation. For example, silver ions, in particular, can be
inserted among the various layers of layered nanoclay by
positioning in a "hole" to maximize favorable interactions between
the positively charged silver ion and the various types of oxygen
in the silicate structure. Silver ions have been shown to have
anti-microbial properties and Laponite that contains intercalated
ionic silver, retains these properties. Intercalation is also
possible with other metal ions, such as copper, zinc, manganese,
etc.
[0050] The metal may also be loaded onto the nanoparticle via ion
exchange. For example, the surface of Laponite platelets is
composed mainly of sodium ions, which exist to balance out the
negatively charged oxygen atoms donated by the silicate structure
in the layer below. When positively charged metal ions are added to
a solution of exfoliated Laponite, a fraction of the surface sodium
ions are displaced by the added metal cations.
[0051] The metal may also be loaded onto the nanoparticle by
adsorption. For example, certain functional groups such as amine,
ammonium, and carboxyl groups are strong binders to the face or
edge of a platelet of Laponite. Metal ions can be modified by the
addition of these ligands so that they are able to bind strongly to
the surface of Laponite. The reaction sequence for one example is
shown below:
2AgNO.sub.3+2NaOH.fwdarw.Ag.sub.2O+2NaNO.sub.3+H.sub.2O
Ag.sub.2O+4NH.sub.3+H.sub.2O.fwdarw.2Ag(NH.sub.3).sub.2OH
[0052] The final product, Ag(NH.sub.3).sub.2OH, is contacted with
Laponite, whereby the Ag(NH.sub.3).sub.2OH binds to the face of the
Laponite.
[0053] In one embodiment of the invention a metal ion is reduced to
a metal (0) in the presence of a starting material, which is
exfoliated to form a nanoparticle. Reduction and exfoliation may
take place in sequence (either step happening first) or
simultaneously upon contacting of the metal with the starting
material/exfoliated nanoparticle. The metal is thereby loaded onto
the surface of the exfoliated nanoparticle.
[0054] In one embodiment of the invention, the metal is silver,
which is loaded onto the nanoparticle via intercalation using the
Tollen's reagent. The Tollen's reagent is a known silver species
able to undergo reduction by either an aldehyde or ketone to form
silver metal (0):
+Ag(NH.sub.3).sub.2OH+glucose.fwdarw.Ag.sup.0
[0055] The composite material may in incorporated into a variety of
systems, materials and compositions, including liquids, solids,
gels, coating compositions, cosmetic and pharmaceutical
compositions and the like. The composite material may be
incorporated into structures or articles of manufacture such as
absorbent articles, wound care articles, soft surfaces, or hard
surfaces. Compositions containing the composite material may be
solutions or dry materials, that are coated, applied, extruded,
sprayed, and so forth as further described below. Such compositions
may have end uses in manufacturing, commercial, industrial,
personal, or domestic applications.
[0056] Systems comprising the composite material can be employed to
bring about certain, desired benefits, for example improved fluid
absorbency, wettability, strike-through, comfort, malodor control,
lubricity, anti-inflammatory properties, anti-microbial properties,
anti-fungal properties, modification of surface friction,
flexibility, transparency, modulus, tensile strength, color
enhancement, viscosity, smoothness, or gel strength.
[0057] In certain embodiments, the presence of the composite
material in a composition does not affect the desirable properties
of the composition, for example transparency. Addition of the
composite material to a liquid composition, for instance, will not
alter the transparency or color of the resultant composition as
compared to the original, liquid material not containing the
composite material. Moreover, since nanoparticles possess large
surface areas, the composite material will also allow for higher
concentrations of metals to be included in the overall formulation,
such as in the treatment of infections.
[0058] Compositions of the invention may comprise the composite
material and any other ingredients appropriate for the intended use
of the compositions. Some compositions of the invention may
comprise: (a) the composite material, which may be an effective
amount of the composite material; (b) a suitable carrier medium;
and (c) optionally one or more adjunct ingredients. The adjunct
ingredients may be, for example, surfactants or charged
functionalized molecules exhibiting properties selected from the
group consisting of hydrophilic, hydrophobic and mixtures thereof
associated with at least some of the composite material, or
both.
[0059] Alternatively, an effective amount of composite material
described above can be included in compositions useful for coating
a variety of soft surfaces in need of treatment. As used herein, an
effective amount of composite material refers to the quantity of
composite material necessary to impart the desired benefit to the
soft surface. Such effective amounts are readily ascertained by one
of ordinary skill in the art and is based on many factors, such as
the particular composite material used, the nature of the soft
surface whether a liquid or dry (e.g., granular, powder)
composition is required, and the like.
[0060] The composition may be applied to the surface(s) by washing,
spraying, dipping, painting, wiping, or by other manner in order to
deliver a coating, especially a transparent coating that covers at
least about 0.5% of the surface, or any greater percentage of the
surface, including but not limited to: at least about 5%, at least
about 10%, at least about 30%, at least about 50%, at least about
80%, and at least about 100% of the surface. Accordingly, the
coating may be continuous or discontinuous.
[0061] If the coating composition is to be sprayed onto the
surface, the viscosity of the coating composition should be such
that it will be capable of passing through the nozzle of a spray
device. Such viscosities are well known, and are incorporated
herein by reference. The composition may be capable of undergoing
shear thinning so that it is capable of being sprayed.
[0062] Suitable carrier mediums for the compositions containing the
composite material include liquids, solids and gases. One suitable
carrier medium is water, which can be distilled, deionized, or tap
water. Water is valuable due to its low cost, availability, safety,
and compatibility. The pH of the liquid, in particular water, may
be adjusted through the addition of acid or base. Aqueous carrier
mediums are also easy apply to a substrate and then dried. Though
aqueous carrier mediums are more common than dry, nonaqueous
mediums, the composition can exist as a dry powder, granule or
tablet or encapsulated complex form.
[0063] Optionally, in addition to or in place of water, the carrier
medium can comprise a low molecular weight organic solvent.
Preferably, the solvent is highly soluble in water, e.g., ethanol,
methanol, propanol, isopropanol, ethylene glycol, acetone, and the
like, and mixtures thereof. The solvent can be used at any suitable
level. Several non-limiting examples, include a level of up to
about 50%, or more; from about 0.1% to about 25%; from about 2% to
about 15%, and from about 5% to about 10%, by weight of the total
composition. Factors to consider when a high level of solvent is
used in the composition are odor, flammability, dispersancy of the
nanoparticles and environmental impact.
[0064] The carrier medium may also comprise a film former, which
when dried, forms a continuous film. Examples of film formers are
polyvinyl alcohol, polyethylene oxide, polypropylene oxide, acrylic
emulsions, hydroxypropylmethyl cellulose.
[0065] Adjunct ingredients that may be used in compositions
containing the composite material include polymers and copolymers
with at least one segment or group which comprises functionality
that serves to anchor the composite material to a substrate. These
polymers may also comprise at least one segment or group that
serves to provide additional character to the polymer, such as
hydrophilic or hydrophobic properties.
[0066] Examples of the anchoring segments or groups include:
polyamines, quaternized polyamines, amino groups, quaternized amino
groups, and corresponding amine oxides; zwitterionic polymers;
polycarboxylates; polyethers; polyhydroxylated polymers;
polyphosphonates and polyphosphates; and polymeric chelants.
[0067] Examples of the hydrophilizing segments or groups include:
ethoxylated or alkoxylated polyamines; polyamines; polycarboxylated
polyamines; water soluble polyethers; water soluble
polyhydroxylated groups or polymers, including saccharides and
polysaccharides; water soluble carboxylates and polycarboxylates;
water soluble anionic groups such as carboxylates, sulfonates,
sulfates, phosphates, phosphonates and polymers thereof; water
soluble amines, quaternaries, amine oxides and polymers thereof;
water soluble zwitterionic groups and polymers thereof; water
soluble amides and polyamides; and water soluble polymers and
copolymers of vinylimidazole and vinylpyrrolidone.
[0068] Examples of the hydrophobizing segments or groups include:
alkyl, alkylene, and aryl groups, and polymeric aliphatic or
aromatic hydrocarbons; fluorocarbons and polymers comprising
fluorocarbons; silicones; hydrophobic polyethers such as
poly(styrene oxide), poly(propylene oxide), poly(butylene oxide),
poly(tetramethylene oxide), and poly(dodecyl glycidyl ether); and
hydrophobic polyesters such as polycaprolactone and
poly(3-hydroxycarboxylic acids).
[0069] Examples of hydrophilic surface polymers that may be
incorporated into the compositions of the invention include, but
are not limited to: ethoxylated or alkoxylated polyamines;
polycarboxylated polyamines; polycarboxylates including but not
limited to polyacrylate; polyethers; polyhydroxyl materials;
polyphosphates and phosphonates.
[0070] Examples of hydrophobic surface polymers that may be
incorporated into the compositions of the invention include
alkylated polyamines include, but are not limited to:
polyethyleneimine alkylated with fatty alkylating agents such as
dodecyl bromide, octadecyl bromide, oleyl chloride, dodecyl
glycidyl ether and benzyl chloride or mixtures thereof; and
polyethyleneimine acylated with fatty acylating agents such as
methyl dodecanoate and oleoyl chloride; silicones including, but
not limited to: polydimethylsiloxane having pendant aminopropyl or
aminoethylaminopropyl groups and fluorinated polymers including,
but not limited to: polymers including as monomers (meth)acrylate
esters of perfluorinated or highly fluorinated alkyl groups.
[0071] Non-polymeric surface modifying materials that may be used
as adjunct ingredients include fatty amines and quaternized amines
including: ditallowdimethylammonium chloride;
octadecyltrimethylammonium bromide; dioleyl amine; and
benzyltetradecyldimethylammonium chloride. Silicone-based
surfactants, fatty zwitterionic surfactants and fatty amine oxides
may also be incorporated into the composition.
[0072] Surfactants are also optional adjunct ingredients.
Surfactants are especially useful in the composition as wetting
agents to facilitate the dispersion.
[0073] Suitable surfactants can be selected from the group
including anionic surfactants, cationic surfactants, nonionic
surfactants, amphoteric surfactants, ampholytic surfactants,
zwitterionic surfactants and mixtures thereof. Examples of suitable
nonionic, anionic, cationic, ampholytic, zwitterionic and
semi-polar nonionic surfactants are disclosed in U.S. Pat. Nos.
5,707,950 and 5,576,282. Nonionic surfactants may be characterized
by an HLB (hydrophilic-lipophilic balance) of from 5 to 20,
alternatively from 6 to 15.
[0074] Mixtures of anionic and nonionic surfactants are especially
useful. Other conventional useful surfactants are listed in
standard texts.
[0075] Another class of adjunct ingredients that may be useful are
silicone surfactants and/or silicones. They can be used alone
and/or alternatively in combination with other surfactants
described herein above. Nonlimiting examples of silicone
surfactants are the polyalkylene oxide polysiloxanes having a
dimethyl polysiloxane hydrophobic moiety and one or more
hydrophilic polyalkylene side chains
[0076] If used, the surfactant is should be formulated to be
compatible with the composite material, carrier medium and other
adjunct ingredients present in the composition.
[0077] The compositions can contain other adjunct ingredients,
including but not limited to alkalinity sources, antioxidants,
anti-static agents, chelating agents, aminocarboxylate chelators,
metallic salts, photoactive inorganic metal oxides,
odor-controlling materials, perfumes, photoactivators, polymers,
preservatives, processing aids, pigments, and pH control agents,
solubilizing agents, zeolites, and mixtures thereof. These optional
ingredients may be included at any desired level.
[0078] Coating compositions comprising the composite material can
be used on all types of soft surfaces, including but not limited to
woven fibers, nonwoven fibers, leather, plastic (for example,
toothbrush handles, synthetic film, filaments, toothbrush
bristles), and mixtures thereof. The soft surfaces of interest
herein may comprise any known type of soft surface, including but
not limited to those associated with disposable absorbent articles
including but not limited to covers or topsheets, absorbent cores,
transfer layers, absorbent inserts, and backsheets including those
outer layers made from breathable and nonbreathable films.
[0079] It should be understood that in certain embodiments, such a
coating composition can be applied to hard surfaces, and provide
benefits thereto.
[0080] In certain embodiments, the soft surface may comprise one or
more fibers. A fiber is defined as a fine hairlike structure, of
vegetable, mineral, or synthetic origin. Commercially available
fibers have diameters ranging from less than about 0.001 mm (about
0.00004 in) to more than about 0.2 mm (about 0.008 in) and they
come in several different forms: short fibers (known as staple, or
chopped), continuous single fibers (filaments or monofilaments),
untwisted bundles of continuous filaments (tow), and twisted
bundles of continuous filaments (yarn). Fibers are classified
according to their origin, chemical structure, or both. They can be
braided into ropes and cordage, made into felts (also called
nonwovens or nonwoven fabrics), woven or knitted into textile
fabrics, or, in the case of high-strength fibers, used as
reinforcements in composites-that is, products made of two or more
different materials.
[0081] The soft surfaces may comprise fibers made by nature
(natural fibers), made by man (synthetic or man-made), or
combinations thereof. Example of natural fibers include but are not
limited to: animal fibers such as wool, silk, fur, and hair;
vegetable fibers such as cellulose, cotton, flax, linen, and hemp;
and certain naturally occurring mineral fibers. Synthetic fibers
can be derived from natural fibers or not. Examples of synthetic
fibers which are derived from natural fibers include but are not
limited to rayon and lyocell, both of which are derived from
cellulose, a natural polysaccharide fiber. Synthetic fibers which
are not derived from natural fibers can be derived from other
natural sources or from mineral sources. Example synthetic fibers
derived from natural sources include but are not limited to
polysaccharides such as starch. Example fibers from mineral sources
include but are not limited to polyolefin fibers such as
polypropylene and polyethylene fibers, which are derived from
petroleum, and silicate fibers such as glass and asbestos.
Synthetic fibers are commonly formed, when possible, by fluid
handling processes (e.g., extruding, drawing, or spinning a fluid
such as a resin or a solution). Synthetic fibers are also formed by
solid handling size reduction processes (e.g., mechanical chopping
or cutting of a larger object such as a monolith, a film, or a
fabric).
[0082] Disposable absorbent articles, such as pantiliners, sanitary
napkins, interlabial devices, adult incontinent devices, breast
pads, shoe insoles, bandages, and diapers typically are made from
absorbent, nonwoven materials (including fibers) and are well known
in the art. These articles typically have a fluid permeable
body-facing side and fluid impermeable garment facing side.
Additionally, such articles may include an absorbent core for
retaining fluids therebetween. Addition of the composite material
to an article of manufacture such as the absorbent core of a
disposable, absorbent article may help control malodor formation
and increase absorbency.
[0083] Other uses for the composite material include but are not
limited to use in dental abrasives for toothpaste, odor absorbents,
and oral rinses. Other uses for the composite material include
ophthalmic solutions and devices such as contact lenses.
[0084] Another embodiment of the invention relates to cosmetic and
pharmaceutical compositions comprising the composite material.
These may be in the form of creams, lotions, gels, foams, oils,
ointments, or powders for application to tissues including skin,
hair, nails, and mucosa such as vaginal or oral mucosa. Such
compositions may be formulated as either leave-on products or
rinse-off products. Alternatively, such compositions may also be in
the form of ophthalmic solutions or ointments, which are applied
directly to the eye.
[0085] In one embodiment, the composition contains an anti-acne
agent such as salicylic acid or benzoyl peroxide.
[0086] In another embodiment, the composition is a personal
lubricant such as those disclosed in U.S. Ser. Nos. 10/137,509;
10/390,511; and 10/389,871, filed May 1, 2002; Mar. 17, 2003; Mar.
17, 2003, respectively. These applications describe warming
lubricant compositions that are non-toxic and non-irritating and
that can be used as personal lubricants designed to come into
contact with the skin or mucosa. When mixed with water, such
compositions increase in temperature or generate warmth. This has a
soothing effect on the tissues to which these compositions are
applied. These compositions are preferably substantially anhydrous
and preferably contain at least one polyhydric alcohol. By
incorporating the composite material into these personal
lubrications, the resultant compositions have a smoother
characteristic and remain as clear solutions, as the composite
material does not detract from the transparency of the
compositions.
[0087] Cosmetic and pharmaceutical compositions may contain a
variety of active agents known in the art such as skin lightening
agents, skin pigmentation darkening agents, anti-acne agents, sebum
modulators, shine control agents, anti-microbial agents,
anti-fungals, anti-inflammatory agents, anti-mycotic agents,
anti-parasite agents, external analgesics, sunscreens,
photoprotectors, antioxidants, keratolytic agents, detergents,
surfactants, moisturizers, nutrients, vitamins, energy enhancers,
anti-perspiration agents, astringents, deodorants, hair removers,
firming agents, anti-callous agents, and agents for hair, nail, or
skin conditioning.
[0088] Formulations for topical or mucosal application are well
known in the art. Excipients used by those skilled in the art in
such formulations may be used with the composite material herein,
provided they are compatible.
[0089] The compositions of the present invention can be applied to
a surface and optionally allowed to dry on the surface, optionally
repeating the application and drying steps as needed. In some
embodiments of the methods described herein, including, but not
limited to when applying more than one coating, it is not
necessarily required to dry the coating(s) between
applications.
EXAMPLES
Example 1
[0090] In order to deposit silver metal on nanoclay, silver ions
were reduced in the presence of Laponite using the Tollen's
reagent, which is able to undergo reduction by either an aldehyde
or ketone to form silver metal via the following reaction:
Ag(NH.sub.3).sub.2OH+glucose.fwdarw.Ag.sup.0
[0091] The Tollen's reagent was prepared by adding two drops of 10%
NaOH to 5 mL of 5% AgNO.sub.3 to form a gray-brown precipitate.
This precipitate was then dissolved by the dropwise addition of 2%
NH.sub.4OH to yield a total Tollen's reagent volume of 30 mL.
[0092] A solution of silver-loaded Laponite XLS was prepared by
adding 600 mg of Laponite XLS to 50 mL of distilled water and using
a magnetic stirrer to exfoliate for 20 minutes. To this solution,
800 mg of glucose were added and the stirring continued for 10
minutes to ensure complete dissolution of the glucose. To this, 10
mL of Tollen's reagent as prepared above were added. After two
hours of continuous stirring, the solution turned golden yellow in
color. Further reaction time yielded a dark amber-brown solution.
Samples prepared for particle size analysis and TEM analysis were
diluted by a factor of 10 to prevent particle aggregation. The
particle size of the nanoparticles dictates the color of the
solution caused by a surface plasmon resonance phenomenon. For
silver particles, a yellow color has been determined to have the
smallest particle size possible. The particle size distribution of
the resulting nanoparticles is shown in FIG. 1.
Example 2
[0093] The formation of silver metal from silver ions was also
investigated using NaBH.sub.4:
4AgNO.sub.3+NaBH.sub.4.fwdarw.4Ag.sup.0
[0094] Dropwise addition of 32 mg of AgNO.sub.3 dissolved in 5 mL
of H.sub.2O to a solution containing 500 mg of exfoliated Laponite
XLS and 4 mg NaBH.sub.4 yielded a golden yellow solution. This
addition order for this particular reaction was determined to give
the smallest particle size.
Example 3
[0095] Nanoparticles of silver-laponite were prepared by reduction
with sodium citrate, although the reduction by this method was more
difficult to control. Citric acid was added to an exfoliated
Laponite XLS solution, followed by the addition of silver nitrate.
10% NaOH was added dropwise to form the sodium salt of citric acid
until the solution turned faintly yellow. In many cases, the
over-addition of sodium hydroxide caused the silver particles to
fall out of solution.
AgNO.sub.3+sodium citrate.fwdarw.Ag.sup.0
Example 4
[0096] Nanoparticles of silver-loaded Laponite XLS can be prepared
by hydrazine reduction as follows: 5 g of Laponite XLS are added to
995 g of deionized water and stirred for 20 minutes to exfoliate
the Laponite XLS. 20 mg of 55% hydrazine hydrate is added to the
Laponite XLS dispersion and the solution is stirred for 1 minute.
77 mg of AgNO.sub.3 is dissolved in deionized water. The AgNO.sub.3
solution is added dropwise to the Laponite--hydrazine solution to
form a golden-yellow solution containing 0.005% silver-loaded
Laponite XLS.
Example 5
[0097] Another solution of silver-loaded Laponite XLS was prepared
similarly to Example 1, but the order of the components was
altered. Glucose and Tollen's reagent were mixed in a separate
vessel and once the color of the solution turned faintly gray, this
mixture was added to the solution of exfoliated Laponite XLS. After
a short period of stirring, the solution turned amber-yellow. This
solution was diluted by a factor of 10 for particle size analysis.
The particle size distribution of the resulting material is shown
in FIG. 2.
Example 6
[0098] A sample was prepared by adding 200 mg of Laponite XLS to
100 mL of water and stirring to exfoliate. The sample was analyzed
for particle size. The results are shown in FIG. 3.
Example 7
[0099] The sample of Example 6 was diluted by a factor of 50. The
sample was analyzed for particle size. The results are shown in
FIG. 4.
[0100] The results of Examples 1-7 indicate that as a solution of
Laponite XLS in water is diluted, the distribution of particle
sizes changes. The particle size of silver-loaded Laponite XLS was
smaller, on average, than Laponite XLS alone, indicating that the
addition of silver to the solution aided in the Laponite XLS
exfoliation process.
[0101] The data for Example 1 shows a single particle size
distribution, averaging 4.1 nm in size. Example 5, on the other
hand, showed a bimodal particle size distribution with the averages
centered on 4.1 nm and 11 nm. This indicates the formation of two
different types of particles. It is possible that this solution
contained silver-loaded Laponite XLS and colloidal silver with no
Laponite core.
Example 8
[0102] To verify that the Laponite XLS was being coated with
silver, TEM (transmission electron microscopic) images and EDX
(Energy Dispersive X-Ray) analysis were performed on Examples 1 and
6. The data confirmed that the composite material of Example 1
contained silver-loaded Laponite XLS particles, as opposed to a
mixture of colloidal silver and Laponite XLS. Elemental analysis
showed the presence of Na, Mg, Si, and Ag (Cu was present in the
TEM grid). The data also revealed that particles of very small size
(.apprxeq.1 nm), determined to be uncoated Laponite XLS, were also
present.
Example 9
[0103] A solution containing silver-loaded Laponite XLS particles
was prepared as follows. 4.51 g of Laponite XLS was added to 900 mL
of deionized water. The solution was stirred for 1 hour and labeled
Solution A. To 400 mL of Solution A, 15 mg of NaBH.sub.4 was added.
This solution was labeled Solution B. 124 mg of AgNO.sub.3 was
dissolved in 5 mL of deionized water; and this was added dropwise
to Solution B to form an amber brown solution of 0.02% silver
loaded onto Laponite XLS. Following the above procedure, 0.01 %,
0.005% and 0.0025% silver loaded Laponite XLS solutions were
prepared. These solutions were analyzed for biocidal activity
against the organisms Staphylococcus aureus and Escherichia coli as
follows. The silver-loaded Laponite XLS solutions were inoculated
with the bacteria and neutralized with Letheen Broth containing
1.5% to neutralize the activity after the appropriate time.
Aliquots were plated using Letheen Agar. The bacterial log
reduction is given in the Table below.
1 E.c. - 5 Sample Conc. S.a. - 5 minute S.a. - 10 min minutes E.c.
- 10 min. 0.0025% 0.8 2.2 3.2 5.3 0.005% 4.8 4.8 5.3 5.3 0.01% 2.2
4.8 5.3 5.3 0.02% 4.8 4.8 5.3 5.3
* * * * *